Interconnect dielectric compositions, preparation thereof, and integrated circuit devices fabricated therewith

ABSTRACT

A novel dielectric composition is provided that is useful in the manufacture of integrated circuit devices and integrated circuit packaging devices. The dielectric composition is prepared by imidizing and curing an oligomeric precursor compound comprised of a central polybenzoxazole, polybezothiazole polyamic acid ester segment end-capped at each terminus with an aryl-substituted acetylene moiety such as an ortho-bis(arylethynyl)aryl group, e.g., 3,4-bis(phenylethynly)phenyl. Integrated circuit devices, integrated circuit packaging devices, and methods of synthesis and manufacture are provided as well.

TECHNICAL FIELD

This invention relates generally to dielectric materials and their usein integrated circuits. More particularly, the invention pertains tonovel dielectric polymer compositions, oligomeric precursors and methodsfor preparing the compositions, and integrated circuit devicesfabricated therewith.

BACKGROUND

Polyimides are known in the art for use in the manufacture of integratedcircuits including chips (e.g., chip back end of line, or “BEOL”), thinfilm packages, and printed circuit boards. Polyimides are useful informing dielectric interlayers, passivation layers, alpha particlebarriers, and stress buffers. Polyimides are particularly useful as aninterlayer dielectric material to insulate the conductor wiringinterconnecting the chips on a multichip module. This is known as “thinfilm” wiring. Multichip modules represent an intermediate level ofpackaging between the chips and the circuit board, and are generallyknown in the art. Multichip modules are made up of multiple layers ofpower, signal, and ground planes which deliver power to the chips anddistribute the input/output signals between chips on the module or toand from the circuit board.

There is a continuing desire in the microelectronics industry toincrease the circuit density in multilevel integrated circuit devices,e.g., memory and logic chips, thereby increasing performance andreducing cost. In order to accomplish these goals, those in the fieldare striving to reduce the minimum feature sizes, e.g.,metal lines andvias, and to decrease the dielectric constant of the interposeddielectric material to enable closer spacing of circuit lines without aconcomitant increase in crosstalk and capacitive coupling. Polyimidesusually have dielectric constants of about 3.0-3.8 and mechanical andthermal properties sufficient to withstand present processing operationsincluding the thermal cycling associated with semiconductormanufacturing. However, there is a need in the art for a dielectricmaterial that would be suitable for use in integrated circuit devices,wherein the material exhibits a lower dielectric constant (e.g., <3.0)than typically exhibited by polyimides and has improved mechanical andthermal properties.

The invention is addressed to the aforementioned need in the art, and,in one embodiment, provides a novel dielectric composition thatrepresents a significant improvement over prior dielectric materialsused in integrated circuit devices. The composition is formed byimidizing and curing an oligomeric precursor compound comprised of acentral polyamic acid or polyamic acid ester segment terminated at eachend with an aromatic species substituted with two or morearyl-substituted ethynyl moieties. These oligomeric compounds,dielectric compositions formed therefrom, and associated methods ofmanufacture and use will be discussed in detail herein.

Compounds that are end-capped with two or more diaryl-substitutedacetylene moieties at each of two termini are known and described, forexample, in PCT Publication No. WO 97/10193. The reference does not,however, describe end-capped oligomeric segments comprised of polyamicacid, a polyamic acid ester, or the like.

U.S. Pat. No. 5,138,028 to Paul et al. is also of interest insofar aspolyimides end-capped with diaryl-substituted acetylene are disclosed.Only one diaryl-substituted acetylene moiety is present at eachterminus, resulting in higher curing temperature and less efficientcross linking than possible with the oligomeric precursor compounds ofthe invention.

John et al. (1994), “Synthesis of Polyphenylenes and Polynaphthalenes byThermolysis of Enediynes and Dialkynylbenzenes,” J. Am. Chem. Soc.116:5011-5012, is of background interest insofar as the publicationdescribes thermal polymerization of substituted enediynes. U.S. Pat. No.5,773,197 to Carter et al. is also a background reference that is ofinterest with respect to the present invention, in that the patentdescribes the manufacture and use of integrated circuit devices in whicha dielectric material contained therein is synthesized on a substrate.

No art of which applicants are aware, however, describes or suggests thedielectric compositions as now provided herein, or the oligomericprecursor compounds that are imidized and crosslinked to form thecompositions. In contrast to the dielectric materials of the prior art,the present compositions provide the following advantages: (1) theprecursor to the present dielectric compositions has a lower solutionviscosity than other polyimide precursors, allowing for superiorplanarization and gap filling; (2) the present dielectric compositionshave a low dielectric constant, less than 3.0, which is lower than thatof currently used dielectric materials; and (3) films of the noveldielectric compositions have superior mechanical properties relative tocurrent dielectric materials used in the manufacture of integratedcircuit devices and packages. The compositions also find utility inlaminates, composites and the like.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the invention to address theabove-mentioned need in the art by providing novel dielectric materialsthat are useful, inter alia, in integrated circuit devices.

It is another object of the invention to provide oligomeric precursorcompounds useful for preparing the novel dielectric compositions.

It is still another object of the invention to provide such oligomericprecursor compounds comprised of a central oligomeric segment end-cappedat each of two termini with an aryl-substituted acetylene moiety such asan ortho-bis(arylethynyl)aryl group.

It is yet another object of the invention to provide such oligomericprecursor compounds wherein the central oligomeric segment is a polyamicacid, a polyamic acid ester, a polybenzoxazole, or a polybenzothiazole.

It is a further object of the invention to provide methods forsynthesizing the oligomeric precursor compounds and methods forpreparing the novel dielectric compositions therefrom.

It is still a further object of the invention to provide end-cappingreagents comprised of aryl-substituted acetylene compounds, suitable forpreparing the aforementioned oligomeric precursor compounds.

It is an additional object of the invention to provide an integratedcircuit device in which metallic circuit lines on a substrate areelectrically insulated from each other by a dielectric material thatcomprises a dielectric composition of the invention.

Still a further object of the invention is to provide an integratedcircuit packaging device (multichip module) that incorporates adielectric material comprising a dielectric composition of theinvention.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing, or may be learned by practice of the invention.

In a first embodiment of the invention, then, an oligomeric precursorcompound is provided that can be imidized and crosslinked to prepare adielectric material, the oligomeric precursor compound having thestructural formula (I)

wherein:

n is an integer of 2 or more;

q is 0 or 1;

R is an oligomeric unit comprised of polyamic acid, a polyamic acidester, a polybenzoxazole or a polybenzothiazole;

R¹ is an aromatic group optionally substituted at one or more availablecarbon atoms with an inert, nonhydrogen substituent and optionallycontaining one or more heteroatoms;

L is a linking group, and, as q may be 0, is optional; and

Ar is arylene optionally substituted at one or more available carbonatoms with an inert, nonhydrogen substituent and optionally containingone or more heteroatoms.

In a related embodiment, the invention pertains to end-capping reagentsuseful in synthesizing the aforementioned oligomeric precursorcompounds, wherein the reagents are comprised of aryl-substitutedacetylene compounds generally having the structural formula (II)

wherein R¹, L, q, n and Ar are as defined above, and Z is a reactivemoiety such as OH, NH₂, COOH, halo, or the like.

In another embodiment of the invention, a novel dielectric compositionis provided by heating the aforementioned oligomeric precursor in amanner effective to bring about imidization of the central “R” segmentof the precursor and crosslinking, or “curing,” at thebis(arylethynyl)aryl-substituted termini. Generally, this involvesheating to a predetermined temperature, at a predetermined heating rate,and a predetermined heating time. Preferably, the temperature forpreparing the dielectric composition from the oligomeric precursorcompound is at least about 250° C., more preferably at least about 400°C. The dielectric composition so prepared has a dielectric constant ofless than about 3.0, a thermal expansion coefficient of less than 10⁻³°C.⁻¹, and a number of advantages chemical and mechanical properties,e.g., enhanced mechanical and polishing characteristics, enhancedisotropic optical and dielectrical properties, low thermal film stress,resistance to cracking, increased breakdown voltage, optical clarity,good adhesion to a substrate, and the like.

In a further embodiment of the invention, an integrated circuit deviceis provided that comprises: (a) a substrate; (b) individual metalliccircuit lines positioned on the substrate; and (c) a dielectriccomposition positioned over and/or between the individual metalliccircuit lines, the dielectric composition comprising an imidized, curedoligomer precursor compound, the precursor compound having thestructural formula (I), i.e., comprising a polyamic acid segment,polyamic acid ester segment, or the like, capped at each terminus with amoiety —Ar(—C≡C—(L)_(q)—R¹)_(n) wherein Ar, L, q, n, and R¹ are asdefined above.

Still an additional embodiment of the invention relates to an integratedcircuit packaging device providing signal and power current to anintegrated circuit chip, the packaging device comprising:

(i) a substrate having electrical conductor means for connection to acircuit board,

(ii) a plurality of alternating electrically insulating and conductinglayers positioned on the substrate wherein at least one of theelectrically insulating layers is comprised of a dielectric compositioncomprising an imidized, cured oligomer precursor compound having thestructure of formula (I), i.e., comprising a polyamic acid or polyamicacid ester segment capped at each terminus with a moiety—Ar(—C≡C—(L)_(q)—R¹)_(n) wherein Ar, L, q, n, and R¹ are as definedabove; and

(iii) a plurality of vias for electrically interconnecting theelectrical conductor means, the conducting layers and the integratedcircuit chip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of an integrated circuitdevice of the present invention.

FIGS. 2-5 show a process for making an integrated circuit device of thepresent invention.

FIGS. 6-8 show an alternative process for making an integrated circuitdevice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Overview and Definitions:

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to specific compositions,components or process steps, as such may vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “and,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “an oligomeric compound” or “an oligomericprecursor compound” includes more than one such compound, reference to“a substituent” includes more than one substituent, reference to “alayer” includes multiple layers, and the like.

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions set outbelow.

The term “oligomer” is used to refer to a chemical compound thatcomprises linked monomers, and that may or may not be linear; in thecontext of the present invention, the “oligomers” are, however,generally linear. Oligomeric “segments” as used herein refer to anoligomer that is covalently bound to two additional moieties, generallyend-capping moieties at each of two termini of the oligomeric “segment.”Typically, the oligomeric precursor compounds herein have a numberaverage molecular weight (M_(n)) in the range of approximately 5000 to20,000 g/mol.

The term “alkyl” as used herein refers to a branched or unbranchedsaturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl,tetradecyl, hexadecyl, eicosyl, tetracosyl and the like, as well ascycloalkyl groups such as cyclopentyl, cyclohexyl and the like. The term“lower alkyl” intends an alkyl group of one to six carbon atoms,preferably one to four carbon atoms.

The term “alkenyl” as used herein refers to a branched or unbranchedhydrocarbon group of 2 to 24 carbon atoms containing at least one doublebond, typically containing one to six double bonds, more typically oneor two double bonds, e.g., ethenyl, n-propenyl, n-butenyl, octenyl,decenyl, and the like, as well as cycloalkenyl groups such ascyclopentenyl, cyclohexenyl and the like. The term “lower alkenyl”intends an alkenyl group of two to six carbon atoms, preferably two tofour carbon atoms.

The term “alkynyl” as used herein refers to a branched or unbranchedhydrocarbon group of 2 to 24 carbon atoms containing at least one triplebond, e.g., ethynyl, phenylethynyl, n-propynyl, n-butynyl, octynyl,decynyl, and the like, as well as cycloalkynyl groups such ascyclooctynyl, cyclononynyl, and the like. The term “lower alkynyl”intends an alkynyl group of two to six carbon atoms, preferably two tofour carbon atoms.

The term “alkylene” as used herein refers to a difunctional branched orunbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such asmethylene, ethylene, n-propylene, n-butylene, n-hexylene, decylene,tetradecylene, hexadecylene, and the like. The term “lower alkylene”refers to an alkylene group of one to six carbon atoms, preferably oneto four carbon atoms.

The term “alkenylene” as used herein refers to a difunctional branchedor unbranched hydrocarbon group of 2 to 24 carbon atoms containing atleast one double bond, such as ethenylene, n-propenylene, n-butenylene,n-hexenylene, and the like. The term “lower alkenylene” refers to analkylene group of two to six carbon atoms, preferably two to four carbonatoms.

The term “alkynylene” as used herein refers to a difunctional branchedor unbranched hydrocarbon group of 2 to 24 carbon atoms containing atleast one triple bond, such as ethynylene, n-propynylene, n-butynylene,and the like. The term “lower alkynylene” refers to an alkynylene groupof two to six carbon atoms, preferably two to four carbon atoms, withethynylene particularly preferred.

The term “alkoxy” as used herein refers to a substituent —O—R wherein Ris alkyl as defined above. The term “lower alkoxy” refers to such agroup wherein R is lower alkyl.

The term “aryl” as used herein, and unless otherwise specified, refersto an aromatic moiety containing one to five aromatic rings. For arylgroups containing more than one aromatic ring, the rings may be fused orlinked. Aryl groups are optionally substituted with one or more inert,nonhydrogen substituents per ring; suitable “inert, nonhydrogen”substituents include, for example, halo, haloalkyl (preferablyhalo-substituted lower alkyl), alkyl (preferably lower alkyl), alkenyl(preferably lower alkenyl), alkynyl (preferably lower alkynyl), alkoxy(preferably lower alkoxy), alkoxycarbonyl (preferably loweralkoxycarbonyl), carboxy, nitro, cyano and sulfonyl. Unless otherwiseindicated, the term “aryl” is also intended to include heteroaromaticmoieties, i.e., aromatic heterocycles. Generally, although notnecessarily, the heteroatoms will be nitrogen, oxygen or sulfur.

The term “arylene” as used herein, and unless otherwise specified,refers to a bifunctional aromatic moiety containing one to five aromaticrings. Arylene groups are optionally substituted with one or moresubstituents per ring as set forth above for substitution of an “aryl”moiety.

The term “halo” is used in its conventional sense to refer to a chloro,bromo, fluoro or iodo substituent. In the compounds described andclaimed herein, halo substituents are generally fluoro or chloro. Theterms “haloalkyl,” “haloaryl” (or “halogenated alkyl” or “halogenatedaryl”) refer to an alkyl or aryl group, respectively, in which at leastone of the hydrogen atoms in the group has been replaced with a halogenatom.

The term “heterocyclic” refers to a five- or six-membered monocyclicstructure or to an eight- to eleven-membered bicyclic heterocycle. The“heterocyclic” substituents herein may or may not be aromatic, i.e.,they may be either heteroaryl or heterocycloalkyl. Each heterocycleconsists of carbon atoms and from one to three, typically one or two,heteroatoms selected from the group consisting of nitrogen, oxygen andsulfur, typically nitrogen and/or oxygen. The term “nonheterocyclic” asused herein refers to a compound that is not heterocyclic as justdefined.

The term “hydrocarbyl” is used in its conventional sense to refer to ahydrocarbon group containing carbon and hydrogen, and may be aliphatic,alicyclic or aromatic, or may contain a combination of aliphatic,alicyclic and/or aromatic moieties. Aliphatic and alicyclic hydrocarbylmay be saturated or they may contain one or more unsaturated bonds,typically double bonds. The hydrocarbyl substituents herein generallycontain 1 to 24 carbon atoms, more typically 1 to 12 carbon atoms, andmay be substituted with various substituents and functional groups.

The term “inert” to refer to a substituent or compound means that thesubstituent or compound will not be modified either in the presence ofthe reagents or under the conditions normally employed in themanufacture of integrated circuit devices. As explained above, and asintended throughout, “inert, nonhydrogen substituents” include, but arenot limited to, halo, haloalkyl (preferably halo-substituted loweralkyl), alkyl (preferably lower alkyl), alkoxy (preferably loweralkoxy), alkoxycarbonyl (preferably lower alkoxycarbonyl), carboxy,nitro, cyano, silyl, trialkylsilyl, and sulfonyl.

The term “available” to refer to an optionally substituted carbon atomrefers to a carbon atom that is covalently bound to one or more hydrogenatoms that can be replaced by a designated substituent withoutdisrupting or destabilizing the remaining structure of the molecule.

“Optional” or “optionally” means that the subsequently describedcircumstance may or may not occur, so that the description includesinstances where the circumstance occurs and instances where it does not.For example, the phrase “optionally substituted” means that anon-hydrogen substituent may or may not be present, and, thus, thedescription includes structures wherein a non-hydrogen substituent ispresent and structures wherein a non-hydrogen substituent is notpresent.

Oligomeric Precursor Compounds:

The dielectric compositions of the invention that are useful, interalia, in the manufacture of integrated circuit devices, are preparedfrom an oligomeric precursor compound having the structure of formula(I)

wherein n, q, R, R¹, L and Ar are generally defined above.

More specifically:

Each Ar group is preferably substituted with two —C≡C—(L)_(q)—R¹ groupsthat are ortho to each other on Ar; thus, in the preferred embodiment, nis 2. Ar is heterocyclic or nonheterocyclic arylene optionallysubstituted at one or more available carbon atoms with an inert,nonhydrogen substituent, as noted above. Preferred Ar groups arenonheterocyclic, including, for example, phenylene, naphthylene,biphenylene, and phenylene, naphthylene and biphenylene optionallysubstituted at one or more available carbon atoms with an inert,nonhydrogen substituent. In a particularly preferred embodiment, Ar isphenylene.

While the linking group L may be present, it is optional. Thus, q is 0or 1. Generally and preferably q is 0. When q is 1 and L is, therefore,present, L normally represents a hydrocarbyl linker such as alkylene,alkylene, or the like, optionally substituted with one or more inertnonhydrogen substituents and optionally containing nonhydrocarbyllinkages, e.g., —O—, —S—, —NH—, or the like.

R¹ is aromatic, and may be heterocyclic or nonheterocyclic, monocyclicor polycyclic, and substituted at one or more available carbon atomswith an inert, nonhydrogen sub stituent. Examples of R¹ sub stituentsinclude phenyl, naphthyl, biphenyl, anthranyl, indenyl, furanyl,pyridinyl, pyrimidyl, thiophenyl, benzofuranyl, benzothiophenyl,indolyl, quinolinyl, and the like.

R is an oligomeric unit comprised of polyamic acid, polyamic acid ester,polybenzoxazole, a polybenzothiazole, or the like, preferably polyamicacid or a polyamic acid ester, but in a particularly preferredembodiment is a polyamic acid ester. In the latter case, the oligomericsegment R comprises the reaction product of (a) a diamine, and (b) adiester diacyl halide formed from reaction of a tetracarboxylicdianhydride with a lower alkanol and, subsequently, with a suitablehalogenating agent such as an oxalyl halide, thionyl, chloride, and thelike. The diamine has the structural formula H₂N—R²—NH₂ in which R² is adifunctional monocyclic or bicyclic aromatic moiety, typically althoughnot necessarily selected from the group consisting of

wherein X is lower alkylene, lower alkenylene, carbonyl, O, S, SO₂,N(Nakl),N(aryl), dialkylsilyl, phosphonyl, if lower alkylene or loweralkenylene, optionally substituted at one or more available carbon atomswith halogen, halo-substituted lower alkyl or phenyl. Specific R² groupswithin the aforementioned include, but are not limited to, thefollowing:

wherein Y is selected from the group consisting of trifluoromethyl,phenyl and phenyl substituted with one or more inert, nonhydrogensubstituents, with phenyl preferred. Particularly preferred aromaticdiamines include, but are not limited to: p-phenylene diamine;4,4′-diamino-diphenylamine; benzidine; 4,4′-diamino-diphenyl ether;1,5-diamino-naphthalene; 3,3′-dimethyl-4,4′diamino-biphenyl;3,3′-dimethoxybenzidine; 1,4-bis(p-aminophenoxy) benzene;1,3-bis(p-aminophenoxy) benzene;2,2-bis[4-aminophenyl]hexafluoropropane; 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane (“3FDA”); and9,9-bis(4-aminophenyl) fluorene (“FDA”).

The R² moiety in the diamine may also be an aliphatic or cycloaliphaticgroup such as cycloalkylene, e.g., cyclohexylene. Suitable aliphaticdiamines include 1,4-diaminocyclohexane and bis (4-aminocyclohexyl)methane, 1,4-diamino-2,2,2-bicyclooctane, 1,3-diaminoadamantane,1,3-bis-p-aminophenyladamantane, etc.

The most preferred diamines for forming the polyamic acid ester segmentare 3,3′-bis-trifluoromethoxy benzidine (“TFMOB”), 4,4-oxydianiline and3,3′-bis-trifluoromethyl benzidine (“BTFB”).

The tetracarboxylic dianhydride has the structural formula

wherein Q is a tetrafunctional aromatic moiety, preferably monocyclic,bicyclic or tricyclic, and is typically selected from the groupconsisting of

Suitable dianhydrides include, without limitation: pyromelliticdianhydride; benzophenone dianhydride; 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride; 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride;bis(3,4-dicarboxyphenyl) ether dianhydride; bis(3,4-dicarboxyphenyl)thioether dianhydride; bisphenol-A bisether dianhydride;2,2-bis(3,4-dicarboxylphenyl)hexafluoropropane dianhydride;2,3,6,7-naphthalenetetracarboxylic acid dianhydride;bis(3,4-dicarboxyphenyl) sulfone dianhydride; 1,2,5,6-naphthalenetetracarboxylic dianhydride; 2,2′,3,3′-biphenyl tetracarboxylicdianhydride; 9,9-bis-(trifluoromethyl) xanthenetetracarboxylicdianhydride; 9-trifluoromethyl-9-phenyl xanthenetetracarboxylicdianhydride; 3,4,3′,4′-benzophenone tetracarboxylic dianhydride; andterphenyldianhydride.

The oligomeric precursor compound (I) is prepared by synthesizing theoligomeric unit R in the presence of a predetermined quantity of anend-capping moiety Z—Ar(C≡C—(L)_(q)—R¹)_(n), wherein R¹, L, q, n and Arare as defined above, and Z is a reactive moiety such as OH, NH₂, COOH,halo, or the like, but is preferably NH₂. Generally, this involves anamidization reaction wherein (a) a diamine H₂N—R²—NH₂, as describedabove, is reacted with (b) a diester diacyl halide formed from reactionof a tetracarboxylic dianhydride, also as described above, with a loweralkanol and halogenating reagent such as an oxalyl halide, in thepresence of (c) the end-capping moiety Z—Ar(C≡C—(L)_(q)—R¹)_(n). Thatis, the diester diacyl halide is formed by sequentially reacting thecorresponding tetracarboxylic dianhydride with a lower alkanol such asethanol and a halogenation reagent such as an oxalyl halide, e.g.,oxalyl chloride, in the presence of the end-capping moiety. The rate ofsubsequent imidization can be varied by employing different alcoholsand/or different ester substituents, as the electronic substituenteffect of various ester substituents (e.g., an ethyl ester substituentas results from reaction with ethanol) will change the reaction rate.Alcohols useful in the aforementioned reaction will be known to thoseskilled in the art and are disclosed in the pertinent literature andtexts, e.g., Advances in Polymer Science: High Performance Polymers, ed.Hergenrother (New York: Springer-Verlag, 1994), at page 139. Suitablediester diacyl chlorides are diethyldichloropyromellitate, diethyldichlorobiphenyl tetracarboxylate and diethyldichloro oxydiphthalate.Other suitable diamines and diester diacyl chlorides will be known tothose skilled in the art such as those disclosed in U.S. Pat. No.4,720,539 and copending commonly assigned U.S. patent application Ser.No. 08/058,303 filed May 10, 1992.

In synthesizing the oligomeric compound (I), the diamine, the diesterdiacyl halide and the end-capping reagent are dissolved in a suitablesolvent, preferably a polar, aprotic solvent such asN-methylpyrrolidone, dimethylacetamide, dimethylformamide,tetrahydrofuran, cyclohexanone, γ-butyrolactone, or the like, in properstoichiometric amounts. Generally, the diamine and diester diacyl halideare present in an approximately 1:1 molar ratio, with the amount ofend-capping reagent Z—Ar(C≡C—(L)_(q)—R¹)_(n) calculated from theCarothers equation to provide the desired molecular weight of theproduct. The oligomeric compound (I) so provided preferably has a numberaverage molecular weight (M_(n)) of about 5000 to 20,000 g/mol. Compound(I) can be isolated and purified using conventional techniques known tothose skilled in the art.

An example of a specific compound of structural formula (I) is asfollows:

and, as may be seen, the polyamic ester substituent is ethyl.

Dielectric Compositions:

The oligomeric precursor compound having the structural formula (I) isreadily converted to a dielectric material by heating to a suitabletemperature to bring about imidization of the oligomeric segment R,chain extension, and crosslinking at the end-capped termini. Thisreaction may be conducted neat or in a solvent, preferably neat.Suitable solvents are those in which the oligomeric compoundsubstantially dissolves and which has a viscosity convenient forcoating, as in the manufacture of integrated circuits, the primaryapplication herein, polymerization is conducted on a substrate. Thesolution will generally comprise from about 5 to 80, preferably 10 to70, weight percent solids. Examples of suitable solvents include, forexample N-methylpyrrolidone, dimethylacetamide, dimethylform amide,diphenylether, and the like. When polymerization is conducted in asolvent, crosslinking and chain extension are controlled to maintainpolymer solubility (B-staging of thermosets).

The time, temperature and heating rate that are most advantageous in theimidization, chain extension, and crosslinking process will vary,depending on the specific oligomeric precursor used. In general, theoligomer is heated to a temperature of at least about 250° C. to bringabout imidization of the central oligomeric segment R, chain extension,and crosslinking of the end-capped termini, with the temperaturemaintained thereat for a time period of at least about 1 hour, andpreferably for 2 hours or more. Then, crosslinking is effected at ahigher temperature, preferably at least about 400° C., with the elevatedtemperature maintained for a time period of at least about 1 hour, andpreferably for 2 hours or more.

This imidization and crosslinking step is preferably conducted on asubstrate. In such a case, the oligomeric precursor compound (I) may beapplied to a substrate using any number of techniques, e.g., solutiondeposition, dip coating, spin coating, spray coating, doctor blading, orthe like. The substrate on which polymerization may be conducted can beany material that has sufficient integrity to be coated with theoligomeric precursor and thermal stability to withstand the elevatedtemperatures used in the polymerization process. Representative examplesof substrates include silicon, silicon dioxide, glass, silicon nitride,ceramics, aluminum, copper and gallium arsenide. Other suitablesubstrates will be known to those skilled in the art. In a multilayerintegrated circuit device, an underlying layer of insulated circuitlines can also function as a substrate.

The dielectric composition so prepared, typically present as a layer ona substrate, has a dielectric constant less than 3.0 and more preferablyless than 2.8 at 80° C. The dielectric composition has a low thermalexpansion coefficient at elevated temperatures (e.g., less than about10⁻³° C.⁻¹ (i.e., 1000 ppm) at 450° C., preferably less than about5×10⁻⁴° C.⁻¹, more preferably less than about 10⁻⁴° C.⁻¹, to avoid filmcracking during subsequent thermal process steps. The dielectriccomposition has enhanced mechanical and polishing characteristics,improved isotropic optical properties, and enhanced dielectricproperties. The composition also has thermal stress of less than 100MPa, preferably less than 50 MPa. Further, the dielectric compositionhas mechanical properties that enable it to be chemically/mechanicallyplanarized to facilitate lithographic formation of multiple circuitlevels in multilevel integrated circuit devices. The dielectriccomposition has increased breakdown voltage, enhanced toughness, andincreased crack resistance, even in high ambient humidity and in a thickfilm. The dielectric composition is optically clear and adheres well tosubstrates. The composition undergoes minimal shrinkage during heating,typically less than about 10%.

Integrated Circuit Devices:

The primary use of the novel dielectric compositions is in themanufacture of integrated circuit devices. An integrated circuit deviceaccording to the present invention is exemplified in FIG. 1, wherein thedevice is shown as comprising substrate 2, metallic circuit lines 4, anda dielectric material 6 of the present invention. The substrate 2 hasvertical metallic studs 8 formed therein. The circuit lines function todistribute electrical signals in the device and to provide power inputto and signal output from the device. Suitable integrated circuitdevices generally comprise multiple layers of circuit lines that areinterconnected by vertical metallic studs.

Suitable substrates 2 comprise silicon, silicon dioxide, glass, siliconnitride, ceramics, aluminum, copper, and gallium arsenide. Suitablecircuit lines generally comprise a metallic, electrically conductivematerial such as copper, aluminum, tungsten, gold or silver, or alloysthereof. Optionally, the circuit lines may be coated with a metallicliner such as a layer of nickel, tantalum or chromium, or with otherlayers such as barrier or adhesion layers (e.g., SiN, TiN, or the like).

The invention also relates to processes for manufacturing integratedcircuit devices containing a dielectric composition as described andclaimed herein. Referring to FIG. 2, the first step of one processembodiment involves disposing on a substrate 2 a layer 10 of anoligomeric precursor compound of the invention such as abis-phenylacetylene end-capped polyamic ester. The oligomeric precursoris dissolved in a suitable solvent such as dimethylpropylene urea(“DMPU”), N-methylpyrrolidone, or the like, and is applied to thesubstrate by art-known methods such as spin- or spray-coating or doctorblading. The solution uniquely has high solids content (e.g. 40-50%)which leads to enhanced planarization. The precursor compound is thenthermally treated as described in the preceding section so as to bringabout imidization, chain extension and crosslinking, thus convertinglayer 10 to a dielectric composition.

Referring to FIG. 3, the third step of the process involveslithographically patterning the layer 10 of dielectric composition toform trenches 12 (depressions) therein. The trenches 12 shown in FIG. 3extend to the substrate 2 and to the metallic studs 8. Lithographicpatterning generally involves: (i) coating the layer 10 of thedielectric composition with a positive or negative photoresist such asthose marketed by Shipley or Hoechst Celanese, (AZ photoresist); (ii)imagewise exposing (through a mask) the photoresist to radiation such aselectromagnetic, e.g., UV or deep UV; (iii) developing the image in theresist, e.g., with suitable basic developer; and (iv) transferring theimage through the layer 10 of dielectric composition to the substrate 2with a suitable transfer technique such as reactive ion blanket or beametching (RIE). Suitable lithographic patterning techniques are wellknown to those skilled in the art such as disclosed in Introduction toMicrolithography, 2nd Ed., eds. Thompson et al. (Washington, DC:American Chemical Society, 1994).

Referring to FIG. 4, in the fourth step of the process for forming anintegrated circuit of the present invention, a metallic film 14 isdeposited onto the patterned dielectric layer 10. Preferred metallicmaterials include copper, tungsten, and aluminum. The metal is suitablydeposited onto the patterned dielectric layer by art-known techniquessuch as chemical vapor deposition (CVD), plasma-enhanced CVD, electroand electroless deposition (seed-catalyzed in situ reduction),sputtering, or the like.

Referring to FIG. 5, the last step of the process involves removal ofexcess metallic material by “planarizing” the metallic film 14 so thatthe film is generally level with the patterned dielectric layer 10.Planarization can be accomplished using chemical/mechanical polishing orselective wet or dry etching. Suitable methods for chemical/mechanicalpolishing are known to those skilled in the art.

Referring to FIGS. 6-8, there is shown an alternative process for makingan integrated circuit device of the invention. The first step of theprocess in this embodiment involves depositing a metallic film 16 onto asubstrate 18. Substrate 18 is also provided with vertical metallic studs20. Referring to FIG. 7, in the second step of the process, the metallicfilm is lithographically patterned through a mask to form trenches 22.Referring to FIG. 8, in the third step of the process, a layer 24 of anoligomeric precursor compound of the invention is deposited onto thepatterned metallic film 16. In the last step of the process, theoligomeric precursor compound is heated to imidize the oligomericcentral segment and crosslink the precursor's termini; imidization andcrosslinking (curing) result in a dielectric material. Optionally, thedielectric layer may then be planarized, if necessary, for subsequentprocess in a multilayer integrated circuit.

The invention additionally relates to an integrated circuit packagingdevice (multichip module) for providing signal and power current to oneor more integrated circuit chips comprising: (i) a substrate havingelectrical conductor means for connection to a circuit board; (ii) aplurality of alternating electrically insulating and conducting layerspositioned on the substrate wherein at least of the layers comprises afilm of a dielectric material of the present invention; and (iii) aplurality of vias for electrically interconnecting the electricalconductor means, conducting layers and integrated circuit chips.

The integrated circuit packaging device represents an intermediate levelof packaging between the integrated circuit chip and the circuit board.The integrated circuit chips are mounted on the integrated circuitpackaging device which is in turn mounted on the circuit board.

The substrate of the packaging device is generally an inert substratesuch as glass, silicon or ceramic; suitable inert substrates alsoinclude epoxy composites, polyimides, phenolic polymers, hightemperature polymers, and the like. The substrate can optionally haveintegrated circuits disposed therein. The substrate is provided withelectrical conductor means such as input/output pins (I/O pins) forelectrically connecting the packaging device to the circuit board. Aplurality of electrically insulating and electrically conducting layers(layers having conductive circuits disposed in an dielectric insulatingmaterial) are alternatively stacked up on the substrate. The layers aregenerally formed on the substrate in a layer-by-layer process whereineach layer is formed in a separate process step.

The packaging device also comprises receiving means for receiving theintegrated circuit chips. Suitable receiving means include pinboards forreceipt of chip I/O pins or metal pads for solder connection to thechip. Generally, the packaging device also- comprises a plurality ofelectrical vias generally vertically aligned to electricallyinterconnect the I/O pins, the conductive layers and integrated circuitchips disposed in the receiving means. The function, structure andmethod of manufacture of such integrated circuit packaging devices arewell known to those skilled in the art, as disclosed, for example inU.S. Pat. Nos. 4,489,364, 4,508,981, 4,628,411 and 4,811,082.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, that theforegoing description as well as the examples which follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

All patents, patent applications, and publications mentioned herein arehereby incorporated by reference in their entireties.

EXPERIMENTAL

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how toprepare and use the oligomers and polymers disclosed and claimed herein.Efforts have been made to ensure accuracy with respect to numbers (e.g.,quantities, temperature, etc.) but some errors and deviations should beaccounted for. Unless indicated otherwise, parts are parts by weight,temperature is in ° C. and pressure is at or near atmospheric.Additionally, all starting materials were obtained commercially orsynthesized using known procedures.

EXAMPLE 1

This example describes synthesis of ortho-bis(phenylethynyl)phenylend-capped poly(amic ethyl ester).

(a) Synthesis of 3,4-Diiodophenylamine:

A 3-neck 1000 mL flask fitted with a water condenser, an overheadstirrer and under nitrogen, was charged with 3-iodophenylamine (74.92 g,0.34 mol). 300 mL of ethanol (EtOH) was added and the 3-iodophenylaminedissolved with stirring. To the solution, mercury (II) oxide (HgO)(55.57 g, 0.26 mol) was added, the resulting bright orange solution waskept under nitrogen. With continues stirring, iodine (I₂)(86.82 g, 0.34mol) was introduced in 10 g increments. The dark orange solution washeated to 50° C. and was left stirring under nitrogen for 24 hours.

The resulting brown solution with dark brown precipitate was dissolvedin ethyl acetate (EtAc) and was filtered through celite. The solutionwas concentrated and extracted with EtAc/sodium bisulfate/brine. Theorganic layer was collected and dried over anhydrous magnesium sulfate.The crude product was subjected to flash chromatography usingEtAc/hexane 1:3 as the eluent. The solvent was evaporated on a rotaryevaporator yielding black crystals. The product recystallized from EtOHand water yielding 20.78 g white crystals (17.6%).

(b) Synthesis of 3,4-Bis(phenylethynyl)phenylamine:

In a 500 mL round bottom flask, dissolved 3,4-diiodophenylamine (15.31g, 44.39 mmol) in 30 ml of acetonitrille (CH₃CN), followed by theaddition of pyridine (5.43 g, 68.66 mmol). To the resulting orangesolution, trifluoroacetic anhydride (15.30 g, 72.84 mmol) was slowlyadded with stirring. The solution was allowed to stir for 1 hour. Thesolution was poured into a 2 L beaker containing 1.5 L ice water. Theresulting suspension was vacuum filtered, washed with water and allowedto air dry. The pink solid was then transferred into a tarred roundbottom flask and was dried under high vacuum, to obtain 19.44 g (99%) ofN-(3,4-diiodophenyl)-2,2,2-trifluoroethanamide as a pink solid.N-(3,4-diiodophenyl)-2,2,2-trifluoroethanamide (19.0 g, 43.09 mmol) wastransferred into a 3 neck 250 mL round bottom flask and dissolved inphenyl acetylene (13.14 g, 14.13 mL, 128.68 mmol) with 50 ml oftriethylamine (Et₃N), followed by the addition of triphenyl phosphine(2.25 g, 8.57 mmol) as a solid. The solution was cooled to −77C, underargon. The resulting orange solution was allowed to warm up to roomtemperature and while under an argon flow, a catalytic amount of copperiodide (CuI) (0.35 g, 1.71 mmol) and bis-triphenyl phospine palladium(II) chloride ((((C₆H₅)₃P)₂)Cl₂) (1.20 g, 1.71 mmol) with 50 mL Et₃N wasadded. The solution was heated to 80° C. with stirring for 12 hours. Thedark brown solution was cooled then extracted into ethyl acetate withdilute HCl and brine. The solvent was removed and the crude product waspurified by flash chromatography using 20% EtAc in hexane as eluent. Amixture of 4.27 g of the trifluoroacetamide-protected product, a lightbrown solid, and 7.91 g of 3,4-bis(phenylethynyl)phenylamine (88%), aviscous brown oil, were isolated. The protected product could bequantitatively converted to the desired product by reacting it with aaqueous potassium carbonate solution.

(3) Synthesis of Ortho-bis(phenylethynyl)phenyl end-capped poly(amicethyl ester), 5K oligomer:

A 50 mL three-neck flask fitted with an overhead stirrer was chargedwith 0.26 g (0.88 mmol) of 3,4-bis(phenylethynyl)phenylamine, 3.44 g(1.21 mmol) of 3,3′-bis(trifluoromethoxy)benzidine (TFMOB) and 17 mlN-methyl-2-pyrrolidinone (NMP). The flask was heated with stirring underan argon stream in order to dissolve the diamine. After a homogeneoussolution was obtained the flask was cooled to 5° C. and a solution of1.35 g (3.88 mmol) of 4,6-dicarbethoxyisophthalic diacylchloride(m-PMDA) in 15 mL of THF was added dropwise. The solution was allowed towarm to room temperature and stir for 24 h. The resulting viscouspoly(amic ethyl ester) solution was precipitated into methanol/water(1:1) filtered and washed with water 3×, methanol 2× and hexane. Theoligomer powder was vacuum dried to constant weight, 2.5 g (˜98%).Molecular weight (5K) was evaluated by GPC, NMR and intrinsic viscositymeasurements.

EXAMPLE 2

Film formation:

The poly(amic ethyl ester) oligomer from Example 1 was dissolved in NMP.A clear solution was formed with a solids content of 45 wt. %. Thesolution was subsequently cast by spin coating onto glass plates to formfilms from 1 to 10 microns thick. The imidization was accomplished byheating the polymer films for 1 hr. each at 200° C., 300° C. and 400° C.under an N₂ atmosphere. The cured polyimide films were subsequentlycooled, slowly, to room temperature. The cured polyimide werecrack-free, exhibited a dielectric constant of about 3.0 at 80° C.,thermal stress of about 45 Mpa, and a thermal expansion coefficient at450° C. of 75×10⁻⁶.

What is claimed is:
 1. An integrated circuit device comprising: (a) asubstrate; (b) individual metallic circuit lines positioned on thesubstrate; and (c) a dielectric composition positioned over and/orbetween the individual metallic circuit lines, the dielectriccomposition comprising an imidized, cured oligomer precursor compound,the precursor compound comprised of a polybenzoxazole,polybenzothiazole, polyamic acid or polyamic acid ester segment cappedat each terminus with a moiety —Ar(—C≡C—(L)_(q)—R¹)_(n) wherein n is aninteger of 2 or more, q is 0 or 1, R¹ is an aromatic group optionallysubstituted at one or more available carbon atoms with an inert,nonhydrogen substituent, L is a linking group, and Ar is aryleneoptionally substituted at one or more available carbon atoms with aninert, nonhydrogen substituent.
 2. The device of claim 1, wherein, inthe precursor compound, n is 2 and q is
 0. 3. The device of claim 2,wherein the precursor compound has the structure of formula (I)

in which n, q, R¹, and AR are as previously defined, and R represents apolyamic acid ester.
 4. The device of claim 3, wherein R comprises thereaction product of: (a) a diamine; and (b) a diester diacyl halideformed from reaction of a tetracarboxylic dianhydride with a loweralkanol and a halogenating reagent.
 5. The device of claim 4, wherein:the diamine has the structural formula H₂N—R²—NH₂ in which R² is adifunctional monocyclic or bicyclic aromatic moiety; the tetracarboxylicdianhydride has the structural formula

wherein Q is a tetrafunctional monocyclic, bicyclic or tricyclicaromatic moiety; and the halogenating reagent is an oxalyl halide.
 6. Anintegrated circuit packaging device for providing signal and powercurrent to an integrated circuit chip, comprising: (i) a substratehaving electrical conductor means for connection to a circuit board,(ii) a plurality of alternating electrically insulating and conductinglayers positioned on the substrate wherein at least one of the layers iscomprised of a dielectric composition comprising an imidized, curedoligomer precursor compound, the precursor compound comprised of apolybenzoxazole, polybenzothiazole, polyamic acid or polyamic acid estersegment capped at each terminus with a moiety —Ar(—C≡C—(L)_(q)—R¹)_(n)wherein n is an integer of 2 or more, q is 0 or 1, R¹ is an aromaticgroup optionally substituted at one or more available carbon atoms withan inert, nonhydrogen substituent, L is a linking group, and Ar isarylene optionally substituted at one or more available carbon atomswith an inert, nonhydrogen substituent; and (iii) a plurality of viasfor electrically interconnecting the electrical conductor means, theconducting layers and the integrated circuit chip.